topic RE: S8 Packet Buffer - Module SK1008-0816 in ExtremeSwitching (EOS)

S8 Packet Buffer - Module SK1008-0816

Rafael1 — Thu, 13 Apr 2017 02:14:00 GMT

Hello guys!

I'm trying to find how much packet buffers a port has on a S8 switch. I came across a datasheet that says that a S8 switchs can have up to 24GB of packet buffer (but it depends on what modules are installed).

Datasheet link: https://cloud.kapostcontent.net/pub/4677c5a4-399e-443f-9d21-8b10bbd4ddac/s-series-data-sheet-1.pdf?k...

I tryed looking for modules datasheets so I can do the math but none of them says how much buffers they have. I'm specially curious about module (SK1008-0816 - PN 9404433).

Do you guys happen to know where I can find this information?

Many thanks!
Rafael

RE: S8 Packet Buffer - Module SK1008-0816

Erik_Auerswald — Thu, 13 Apr 2017 12:47:00 GMT

Hi,

the S140 and S180 FAQ (see this thread) contains information about per port buffer sizes on page 19.

Thanks,
Erik

RE: S8 Packet Buffer - Module SK1008-0816

Rafael1 — Thu, 13 Apr 2017 17:34:00 GMT

Thank you so much Erik!

A followup question if I may. On the FAQ you pointed out it says that S150 I/O modules have 128MB of buffer on each 10G port. Is it correct to assume that if a burst traffic is ingressing on one of those 10G ports, it will need to consume 128MB of that buffer before a drop occurs? What I'm trying to understand is how this module handles bursty traffic.

Many thanks!!

RE: S8 Packet Buffer - Module SK1008-0816

Erik_Auerswald — Thu, 13 Apr 2017 17:46:00 GMT

Hi Rafael,

if it only were so easy...

I did some tests with an S150 class SSA a while back, using 1G ports at 100Mbps. Without any QoS configuration, sending 110Mbps data to one 100Mbps port resulted in a steady buffer use of about 4MiB (after ramp-up to fill the buffer) before dropping packets, inducing about 340ms of latency. The 1G port is documented in the FAQ as having 21.3MB of packet buffer, so obviously not all of that was used. I used two input ports to one output port for the tests.

I did not find any way to configure how much packet buffer to use on the S-Series. For EXOS, there is a way to display and configure packet buffer sizes, see How to change port buffer size.

Thanks,
Erik

RE: S8 Packet Buffer - Module SK1008-0816

Rafael1 — Thu, 13 Apr 2017 17:50:00 GMT

Erik,

Actually this info helps me a lot!

Thank you so much!